Helicopter device



G. DE BOTH EZAT HELICOPTER DEVICE March 12; 1940.

Fi led Dec. 30, 1937 4 Sheets-Sheet 1 ATTORNEYS larch 12, 1940.

HELICOPTER DEVICE 4 Sheets-Sheet 2 Filed Dec. 30, 1937 QM Nm Q Q4 e INVENTOR W 4".

QZMMPW ATTORNEYS March '12, 1940. G. DE BOTHEZAT 2,192,881 HELICOPTER DEVICE 7 Filed Dec. :50, 1937 4 Sheets-Sheet a L2fa INVENT R h W @7 8. $15.9, MAM;M

' ATTORNEYS March 12, 1940. DE BQTHEZAT 2,192,881 HELICOPTER DEVICE Filed Dec. 30, 1937 4 Sheets-Sheet 4 INVENTOR ATTORNEYS Patented Mar. 12, 1940 HELICOPTER DEVICE George de Bothezat, New York, N. Y., assignor to Helicopter Corporation of America, Long Island City, N. Y., a corporation of New York Application December 30, 1937, Serial No. 182,400

7 Claims.

This invention relates to flying devices of the helicopter type andparticularly to such a device adapted for lifting a part or all of the weight of the user, and is directed to improvements on the helicopter device disclosed in my co-pending application Serial No. 92,307.

The primary object of the invention is to provide a helicopter device permitting the user to walk and run faster and jump higher than normally, and which, when desired, will lift and transport the user under simple control and manipulation by him.

Another object of the invention is to provide such a device which can stand'on the ground by itself, which will protect the feet and legs of the user in case of a rough landing and which will nevertheless permit free leg movements of the user when he desires to walk or run with the device along the surface of the ground.

Still another object of the invention is to provide in such a device an improved construction for mounting and driving the lifting screws.

Further objectsof the invention, particularly in providing such a helicopter device which will be simple and light in structure, inexpensive in cost, and efficient in operation, will appear from the following specification taken in connection with the accompanying drawings, in which Fig. 1 is a side elevational view showing one form of the machine of this invention standing on the ground;

' Fig. 2 is a perspective view of the framefor such machine;

Fig. 3 is an elevational view of the machine with the user standing on the ground;

Fig. i is a vertical section along the line t il of Fig. 1 illustrating the mounting and driving To cross piece It is suitably secured a belt 28 construction of the screws;

Fig. 5 is a horizontal section along the line 6--6 of Fig. 4 in reduced scale;

Fig. 6 is an alternate construction for mounting and driving the screws;

Fig. 7 is another alternate construction for mounting and driving the screws; Fig. 8 is a horizontal section along the line 8-8 of Fig. 7 in reduced scale;

Fig. 9 is a horizontal section along the line -9-9 of Fig. 7 in reduced scale;

Fig. 10 is a horizontal section along the line Ill-l0 'of Fig. 7 in reduced scale;

Fig. 11 is a side elevational view showing an-. other form of the machine of this invention standing on the ground;

Fig. 12 is a plan view of the'machine of Fig. 11;

Fig. 13 is a front elevational view of the machine of Fig. 11, with parts omitted for clarity:

Fig. 14 is an enlarged elevational view of the lower portion of the machine of Fig. 11; and

Fig. 15 is a plan view of the portion of the machine shown in Fig. 14.

In a specific embodiment of the invention shown in Fig. 1, the paired helicopter screws In, H are driven by theair-cooled internal combustion engine [2 located below the screws. The engine It is of the two cylinder type and has its crankshaft connected to the screws I0, I I through I slightly larger thanthe outer diameter of the engine.

The whole system of screws and engine is 'mounted at the top of a frame 14 made of two spaced uprights l5 and I6 connected by cross pieces ll, it, it and 20, the uprights'and cross pieces being preferably of hollow steel tubing. Each of the uprights lt and I t has a portion shaped like a U lying on its side with the yoke 2| thereof to the front and with its side 22 above the other side 23. At the rear of the upper side 22 each upright of the frame extends upwardly and slightly forwardly, as at 24. At the top of the uprights they are attached to the under side of the engine 62.

Cross pieces l9 and it are positioned respectively at the forward end and slightly above the rear end of each upper side 22 of the U portions. Extending downwardly from the cross piece is, preferably at its mid' length, is a tube 25; and from the lower end of tube 25 to cross piece it] is a tube or member 26 on which is mounted a saddle 21 for supporting the user of the device.

which is to be strapped around the waist of the user. Cross piece 20, connecting the yokes 2! of the U portions, may serve as a foot rest for the user. (,ross piece H is near the top of the uprights.

With a frame of theabove construction the device will support itself upon the ground as shown in Fig. 1, while enabling the user to stand with the device (as shown in Fig. 3) when the air screws l0 and II are running and to walk and jump with it without having it impair his leg movements. In flight, the user may set on the saddle 21 and may also rest his feet upon the cross piece 20, as shown i Fig. 1. In landing with the device, as in a j p, the user may the cross piece 20 and thereby have the frame absorb the entire shock of landing.

Figs. 4 and. 5 illustrate a construction for mounting and driving the air screws- Thedrive shaft of the engine extends upwardly through a gear .case 35, the lower portion 3ia of which is secured to the top of the engine casing as at Ma (Fig. 2). The upper portion 3|b of 'gear. case 3| is cylindrical in shape. The two portions Sid and 3lb are connected by a horizontal portion 3Ic. The shaft 30 is enclosed by a tubular member 32, the lower end of which, 32a, is secured to the horizontal portion Me of the gear case and is crescent shaped as shown in Fig. 6, so as to accommodate the reduction gearing 33 in the open part of the crescent. This reduction gearing 33 consists of a gear 34 mounted upon and secured to the drive shaft 30, of gears 35a and 35b mounted upon and secured to a vertical stub shaft 36 having stationary bearings, the lower end of shaft 36 being seated in the horizontal portion 3 lo of the gear case and the upper end of the shaft being seated in a horizontal extension 32c of annular gear 31.

tubular member 32, and of annular gear 31 secured to the hub 38 of air screw lll. Gear 34 meshes with gear 35a and gear 35b meshes with tively small number of teeth, while gears 35 and 31 have'a relatively large number of teeth. This reduction gearing 33 produces a direction of rotation of air screw I I which is opposite to that of shaft 30.

Hub 38 rotates about tubular member 32 and is mounted and supported thereon by the frictionless bearing 39. This bearing is of a type which withstands both axial and radial forces.

Gear case 3| is preferably provided with an annular ring 3|d that fits between cylindrical portion 3") of the case and a cylindrical lip 38a at the underside of the hub,-thereby completely enclosing the gearing in gear case 3|. Suitable bearings 40 may be provided between the ring 3ld and the hub 38.

Drive shaft30 has avertical extension 30a, connected thereto by a flexible coupling 3%.

Shaft extension 30a is enclosed by a tubular member 4| having a shoulder 4la which rests upon the upper end of tubular member 32, and having a lip 4") which fits tightly around the inside of member 32. The upper end of member 4| bells out as at Mo, to form a housing for epi-' cyclic or planetary reduction gearing 42. This consists of the annular gear 43 secured to housing Me, of gears 44a and 44b mounted upon and secured to ashaft 45 and of annular gear 46 secured to the hub 48 of air screw l0. Shaft 45 is rotatably mounted upon an arm 41 which is secured to and rotates with the shaft extension 30a. Gear 44a meshes with annular gear 43and gear 44b meshes with annular gear". The .train value of the planetary'gearing 42 is such that the direction of rotation of the air screw i3 is the same as that-of shaft 30.

Hub 43 rotates about shaft extension 300. and is mounted and supported thereon by the frictionless bearing 49. This bearing is of a type which withstands both axial and radial forces. This hub 48 is preferably provided with a bearing 50 between a cylindricallip 88a at the underside of the hub and the upper end of housing tic.

The small air screw i3 is secured directly to shaft extension 30a above the hub 33. The air Gears 34 and 35b have a rela-- The drive shaft 33 of the engine extends up- Ela of which is secured to the top of the engine. The hub 32 of air screw H is rotatably mounted upon the upper portion Gib of member 6| by means of the frictionless bearing 63. This bearing is of a type which withstands both axial and radial forces. 5

Above hub 62 is a tubular member 64 surrounding shaft 30 and also surrounding shaft extension 600., the latter being connected to shaft 63 by the flexible coupling 30b. The lower end of member 64 is bell-shaped, as at 64a to provide a housing for the epicyclic or planetary gearing 65. This gearing consists of annular gear 56 secured to housing 64a, of gears 61a and 61b mounted upon and secured to a shaft 68 and of an annular gear 69 that is secured to the hub 32 of air screw H. Shaft 68 is rotatably mounted upon an arm 10 which is secured to and rotates with shaft 60. Gear 31a meshes with annular gear 66 and gear 61b meshes with annular gear 39. The train value of the planetary gearing 65 is such that, assuming tubular member 64 remains stationary, the direction of the rotation of the air screw l l is opposite to that of shaft 60.

Hub 62 is preferably provided with a bearing H between a cylindrical lip 62a at the upper side of the hub and the lower end of housing 64a.

The upper portion of tubular member 64 is bell-shaped, as at 641), to provide a housing for the epicyclic or planetary reduction gearing 15. This consists of annular gear 16 secured to housing 64b, of gears 11a and 11b mounted upon and secured to a shaft 18 and of an annular gear 73 secured to the hub 12 of air screw l0. Shaft 18 is rotatably mounted upon an arm which is secured to and rotates with shaft extension 60a. Gear 11a meshes with annular gear 76 and gear 11b meshes with annular gear 13. The train value of the planetary gearing 15 is such that, assuming tubular member 64 remains stationary, the direction of the rotation of the air screw i3 is the same as that of shaft 60. Thus, the train value of the planetary gearing 15 is in the opposite sense relative to that of the planetary gearing 65; that is, if the train value of the gearing 65 is less than one, the train value of the gearing I5 is greater than one. This relationship in the train values of gearing 65 and I5 is obtained in the construction illustrated by having corresponding annular gears 65 and 16 of the two gearings of different diameter, the former smaller than the latter.

Hub 12 rotates about shaft extension 600. and is mounted and supported thereon by the frictionless bearing 83. This bearing is of a type which withstands both axial and radial forces. Hub I2 is preferably provided with a bearing M between a cylindrical lip 12a at the under side of v the hub and the upper end of housing 64b.

The small air screw I3 is secured directly to shaft extension 30a above the screw Ill. The air screw l3 thus rotates in the same direction and with the same speed as drive shaft 60.

With the construction shown in Figs. 4 and 5, the number of revolutions of each of the air screws Wand it bears a fixed relation to the number of revolutions of the engine, and thus, to each other. That the speed of screw it bears a fixed relation to the speed of shaft 33 is obvious from the character of the gearing 33. That the speed of screw it bears a fixed relation to the speed of shaft 30 is due to the fact that one of the non-planetary gears-the annular gear 43-is maintained stationary relative to the engine case. This is effected by means of tubular members GI and 32 and by the gear case 3|.

The feature of the construction shown in Fig. 6 is that maximum efliciency is obtained for the liftingscrews I0 and II. This is due to the fact that, with such a construction, there is no rotation of the resulting slip-stream produced by the two oppositely rotating lifting screws I0 and II-, with the result that the race-rotation loss (i. e'., the loss due to the rotation of the slip-stream), is entirely eliminated. Rotation of the resulting slip-stream is eliminated by the action of the tubular member 64.

In explanation, since lifting screws II! and an rotate in opposite directions, the air resistance torques of the screws act in opposite directions. In other words, the reaction torque applied to member M as an incident in driving air screw it,

is in the opposite direction to the reaction torque applied to the same member as an incident in driving air screw i I5. These reaction torques thus tend to balance one another. If the air resistance torques of the lifting screws are equal in magnitude, the reaction torques applied to member M are cqual'in magnitude but opposite in direction, and thus are exactly balanced so that tubular member 66 remains stationary. If the air resistance torques of the lifting screws are not exactly equal, so that there is a slight difi'erence in magnitude between the reaction torques applied to member 6 3, the tubular member M will rotate slightly. This rotation of member Ed tends to equalize the air resistance torques. Thus, the

torques of the lifting screws are equalized.

It is to be noted that in the construction illustrated in Fig. 4, the gears 35a and 35b and the stub shaft 36 do not transmit vertical stresses from the horizontal portion 320 to the horizontal portion tic, such forces being carriedby the sta tionary vertical portions 32a. If desired, however, the stub shaft 3% may be arranged to carry some of such vertical stresses, and thereby obtain a better balanced condition of stresses in gear casing 3i and member 32. For example, stub shaft 36 may be fitted into bearings at the ends thereof of a type that withstands both axial and and which are of the type which withstands both axial and radial forces.

Figs. 7, 8, 9 and 10 illustrate an alternate construction for mounting and driving the air screws. In this construction the engine H2 is positioned between the air screws I0 and H, and in addition,

the engine cooling screw I3 is positioned between the two air screws. a

The engine H2, and the screws driven thereby, are secured to the top of the framev I4 (Figs. 1 and 3) through a member I3I, the lower portion i3Ia of which is provided with suitable means for connecting it to the frame M. An upper and horizontal portion or portions I3Ic of member I3I is provided with a plurality of bearings 200 for supporting the lower ends of a similar number of short vertical shafts I36. Preferably there are three shafts I36, and thus three bearings 200, arranged equi-distantly about the engine drive In another alternate arrangement shaft I30, as shown in Fig. 10. The upper ends of these shafts I36 cooperate. with bearings 2!" which are secured to the under side 202 of the engine casing 203. Each of the bearings 200 and 20! is of the type that withstands both axial and radial forces.

The hub of air screw II rotates about a vertical portion I3Ib of member BI and is mounted and supported thereon by a frictionless bearing 205. This bearing is of the type that withstands both axial and radial forces.

The engine II2 drives air screw I! through the reduction gearing I33. This consists of a small gear 134- mounted upon and secured to a portion of the vertical drive shaft I30 which extends below the gear casing 203, of an annular gear I31 secured to or formed upon an axial extension 20% of hub 2M, and of a plurality of sets of gears I35a, I35b. Each such set, of which there are .three in the construction shown, consists of a relatively large gear I35a and a somewhat smaller gear I351), each formed upon, or secured to, shaft H35, with gear I35a meshing with gear I34 and with gear 835?) meshing with annular gear I31.

This reduction gearing I33 produces a direction the inside of the vertical portion I3ib of member BSI.

The air screw it and the engine cooling screw it are positioned above engine H2. These screws, together with the gearing therefor, are attached to the engine as a unit by the clamping nut 2E5 and the bolts 2H9. Clamping nut 2I5 engages a threaded portion of the drive shaft E30 which extends above the upper side 2% of the engine casing 203, and serves to axially secure a rotating member 2H against the shoulder 2 it! formed on drive shaft I39. Bolts 2E9, positioned around the engine casing, secure a stationary member 226 to such casing,

Above stationary member 220 is positioned a second stationary member 22L Members 223) and 2M are secured together by a plurality of shafts 222 (preferably three, as illustrated, see Fig. 9), the lower and upper ends of each of wh ch are respectively journaled in bearings 223 and 224, these bearings being secured respectively on members 220 and ZZI, and being of the type which withstands both axial and radial forces.

The hub 230 of upper air screw it rotates inside an upwardly extending lip 23! on stationary member 22 I, and is mounted and secured thereon by the frictionless bearing 232, this hearing being of the type that withstands both axial and radial forces.

Air screw Ill is driven by engine H2 through the eplcyclic or planetary reduction gearing I42. This consists of the annular gear 3 secured to stationary member 22I, of an annular gear I46,

with gear lfla meshing with annular gear E43 and with gear [44b meshing-with annular gear I 46. Sleeve 235 is rotatably mounted upon a vertical rod 236 which extends through apertures in two radial arms 23l, 238 formed on rotating member 2, this member being secured to drive shaft I30, as by the key 239, so as to rotate therewith. The lower end of rod 236 is provided with a flanged head 240 which sits in a suitable recess in arm 231. The upper end of rod 236 is threaded to receive the nut 25! which secures the rod in place. Between the rod 236 and sleeve 235 are two suitable frictionless bearings 242 and 243, the former at the bottom and the latter at the top of the sleeve. The diameter of the rod 236 preferably increases, as at 244, just below the upper bearing 243 so as to position the sleeve 235 and its gears U la, 4b between the arms 237, 238.

The train value of the planetary gearing I is such that the direction of rotation of the air screw I0 is the same as that of shaft I30.

The hub of the engine cooling screw I3 is a ring 250 which rotates about a downwardly projecting lip 25I on the stationary member HI, and is mounted and secured thereon by the frictionless bearing 252.

The engine cooling screw I3 is driven by engine H2 through the gearing 255. This consists of a gear 256 formed upon, or securedto, rotating member 2| 1, of an annular gear 251 formed upon, or secured to, an annular ring 258 which is secured to ring 250- at the under side thereof, and of a plurality of sets of gears 250a, 23%. Each such set, of which there are three in the construction shown, consists of a gear 250a and. a somewhat larger gear 260b, each formed upon, or secured to, one of the shafts 222, with gear 260a meshing with gear 256 and with gear 2511b meshing with annular gear 257. The train value of this gearing 255 is such that the speed of the engine cooling screw is substantially greater than that of the air screws l0 and II, and is of substantially the same speed as that of drive shaft I30. The di-' rection ofrotation of the engine cooling screw l3, in conjunction with the angle of its blades, is, such as to force air from above the screw down over the cylinder heads of the engine.

With the arrangement of the engine I I2, air screws l0 and II and engine cooling screw I3 as illustrated in Figs. 7-10, it is desirable to provide a cowling 210 about the engine extending upwardly past the cooling screw l3 for directing over the cylinder heads of the engine the air currents which such screw produces. Cowling 210 may be suitably secured to the ends of the cylinder heads, as at 2'", and may be formed in suitable sections to facilitate attachment and removal. side the cowling for further directing the cooling currents over the cylinder heads and for preventing the escape of cooling currents between the cylinders. Also, if desired, the inner portion of screw II may be covered with a light metallic sheet, such as duralumin, to protect that portion of the screw from the exhaust heat and fumes from the engine. Such covering may, for example, extend outwardly for about 20% of the radius of the screw.

In order to completelyenclose the gearing M2 and 255 in those places where it is not already enclosed by the construction heretofore described, the stationary member 220 is provided withan upwardly extending lip 215 which overlaps the annular ring 258. A suitable bearing 273 may be provided between the lip 2'95 and the ring 258.

If desired, baiiles may be provided in- Also, the aperture in hub 230 in axial alinemen' with the drive shaft I 30 may be enclosed by a removable cap 218.

The drive for the air screws shown in Figs. 7-li is in some respects similar to that shown in Figs 4 and 5. Thus, in each construction the numbei of revolutions of each of the air screws bears a fixed relation to the number of revolutions of the engine, and thus to each other. Further, this relationship is obtained in each construction by an epicyclic gear system for the upper air screw II and a non-epicyclic gear system for the lower air'screw III.

One of the features of the construction of Figs. 7-10 is a well balanced gear drive providing a balanced distribution of the lifting forces about the engine drive shaft. Another feature is the saving in weight and space which results from this construction. Still another feature is the emcient manner in which the engine is cooled,

thus enabling a maximum of the developed power The frame 3 of the machine is similar to the I frame I4 shown in Figs. l-3, tothe extent that it includes two spaced up-rights 3I5 and 3I6 connected by cross-pieces 3I1 3I8, 3I9 and 320, with the up-rights each having a portion shaped like a U lying onits side with the yoke 32I thereof to the front and with its side 322 above the other side 323, all corresponding respectively to I5, I6, ll, i8, i9, 20, 2d, 22 and 23 of Figs. 1-3. Frame 393. is also provided with a saddle and belt similarly as in Figs. 1-3.

Frame 3 includes in addition a guard for protecting the user in the event the machine should turn over frontwards, as for example, when making a landing. This guard consists of two substantially vertical arc-shaped members 325, 326, positioned in front of the user with the upper and lower ends of each such member merging with, or being connected to, the upper and lower ends, respectively, of the corresponding up-rights 3I5, 3I6 of the frame 3. The upper ends of upright 3i 5 and member 325 are preferably connected to the upper ends of upright 3| 6 and member 326, as by the cross-pieces 321. These strengthen the framework and provide a point of connection with the motive unit 300.

The lower end of each member 325, 326 preferably includes a horizontal portion 333 parallel to, in the same plane as, and positioned a short distance from the portion 323 of the corresponding tip-right, with the rear ends of such horizontal portions 323 and 333 connected by a short transverse portion 334. The portions 333 thus function similarly as portions 323 in enabling the machine to support itself upon the ground, as shown in Fig. 11 while also enabling the user of the machine to stand when the air screws I0, II are running, and to walk and jump with it without struction, providing what may be termed cater- 75 pillar skis at each side of the machine, facilitates landings which are made with a slight forward motion, and also facilitates handling the machine upon the ground, such as rolling it to and from its hangar, etc.

The'frame 314 preferably includes two rearwardly extending members 340, Ml, connected respectively at their front ends to cross-pieces 3", 319. Upon members 340, SM are mounted two fins 342, 343. Fin 342 is a substantially vertical fin positioned inside the slip stream ofthe air screws [0, ii, and serves to damp rotary motion of the machine around a vertical axis, both when hovering and when in forward motion, and also serves to secure an even forward motion. If desired, the fin may be mounted at a small angle from the vertical, the direction and amount of the angle being such as to produce, as a result of the air fiow down past fin 342, a force which just neutralizes any force which might tend to cause rotation of the frame of the machine about a vertical axis.

Fin 343 is a substantially horizontal fin positioned outside the slip stream of the air screws ill, II, but sufiiciently close thereto to have a small current of air impinged upon its upper surface. This fin 343 serves to provide stability about a transverse horizontal axis and to prevent nose diving of the machine in flight. If desired, the fin may be mounted at a small angle to the horizontal to produce a slight negative lift by virtue of the air flow down past the fin.

While fins 342 and 343 are illustrated as stationarily mounted upon the rearwardly extending members 340, 3, either or both of such fins may be pivotally mountedfin 342 about a vertical axis and fin 343 about a horizontal axis-Fin any suitable manner, with suitable controls therefor extending to the user so that he may adjust them in flight, as desired.

I claim: 1. In a machine ofthe helicopter type having a plurality of lifting screws driven by an internal combustion engine in such manner that the lifting torques substantially balance, and in which said screws and engine are positioned above the head of the operator; a frame fastened to said engine extending downwardly therefrom and having means for supporting at least a part of the weight of the operator by the vertical thrust of said lifting screws, said frame'extending downwardly below the waist-line of the operator in two portions, one at either side of the operator and at a sufficient distance apart as not to interferewith the free leg movements of the operator,

and terminating approximately at the horizontal plane in which lie the operator's knees when, in using the machine, he is in standing position.

2. A device as set forthin claim 1 in which the downwardly extending portions of the frame are each shaped like a U lying on its side with the yoke thereof to the front and with its sides in substantial vertical alignment, the lower side of the U being in approximately the horizontal plane of the knees of the operator when, in using the machine, he is in standing position.

3. In a machine of the helicopter type having a plurality of lifting screws driven by an internal combustion engine in such manner that the lifting torques substantially balance and in which said screws and engine are positioned above the head of the operator, a frame fastened to said engine comprising two spaced uprights each having its lower portion shaped like a U lying on its side with the yoke thereof to the front and with its sides in vertical alignment, the upper portion of each upright extending from the rear portion.

of the upper side of said U portion upwardly and slightly forwardly to the engine; cross pieces connecting said uprights, two of said cross pieces being positioned near the front and rear portions of the upper sides of said U portions; and a saddle for the operator supported between said uprights by said two cross pieces, the heights between the two sides of each of said U-shaped portions and between the saddle and the lower side of each of said U-shaped portions being such that a substantial portion of the legs of the operator extend below the lower side of each of said U-shaped portions when theoperator is in standing position astride the saddle, thereby enabling the operator to walk or jump with the machine as well as ride during flight.

4. A device as set forth in claim 1 in which the frame includes members for guarding the operator of a machine, said members extendin from the topto the bottom of the said frame in front of the operator.

5. In a machine of the helicopter type having a plurality of lifting screws driven by engine means in such manner that the lifting torques substantially balance and in which said screws and engine means are positioned above the head of 'the operator, a frame fastened to said engine means and extending downwardly therefrom, the lower portion of said frame including two U- shaped portions positioned on either-side of the operator with the yokes of such portions to the front and with the lower sides thereof positioned atabout the level of the operators knees when, in using the machine, he is in standing position, said frame also including two arcuate guard members positioned in front of the operator with the upper and lower ends of said guard members secured respectively to the top of said framev and to the lower sides of said U-shaped portions.

6. In a machine of the helicopter type having a plurality of lifting screws driven by engine means in such manner that the lifting torques substantially balance and in which said screws and engine means are positioned above the head of the operator, a frame fastened to said engine means and extending downwardly therefrom, the lower portion of said frame including two U- shaped portions positioned on either side of the operator with the yokes of such portions to the front and with the lower sides thereof positioned at about the level of the operator's knees when. in using the machine, he is in standing position, the lower side of each of said U-shaped portions including a plurality of rollers mounted thereon and an endless belt extending around said rollers.

7. A device as set forth in claim 5 in which the lower ends of said guard members extend, alongside, parallel to, and spaced at short distance from,

the respective lower sides of said U-shaped portions, and in which a plurality of rollers are mounted between the lower end of each guard -member and the corresponding lower side of the U-shaped portions, with an endless belt extending around said rollers at each side of said frame.

GEORGE Dl BOTHEZAT. 

